Axonal projections and functional recovery following fascicular repair of the rat sciatic nerve with Y-tunnelled silicone chambers

The projection of regenerating axons and the specificity of motor reinnervation were studied after repair of the transected rat sciatic nerve with Y-tunnelled silicone chambers. This geometry was used experimentally to face either the proximal tibial or peroneal fascicle with two distal fascicular options usually the distal peroneal and tibial fascicle. A 4 mm gap separated the proximal and distal fascicles. Four weeks after the repair, preferential motor reinnervation could be demonstrated and there were always more axons projecting towards the distal homonymous fascicle. In contrast, if the distal stumps were disconnected from the target no fascicle specific projection of axons was observed. This was true even if segments from the median and ulnar nerve were used to replace either the distal tibial or peroneal segments. It appeared as though the size and not the type of fascicle determined the number of attracted axons. The results suggest that there is no fascicle specific guidance of regenerating nerve fibers.